A new preliminary impact study signals a dramatic advance for Seabridge Gold’s (TSX:SEA) (NYSE:SA) KSM project in northern British Columbia, the world's largest undeveloped gold-copper project by reserves, It is only the second metal mine in five years to receive environmental approval from the federal and provincial governments, received late in 2014 after nearly seven years of assessments. Seabridge now plans a much larger operation than projected in last month’s preliminary feasibility study, with better environmental mitigation and economics. KSM would now produce one million ounces a year for the first seven years of operation. Despite the increased production (mill throughput of 170,000 tonnes per day, 40,000 tonnes more than the earlier study) Seabridge says initial capital costs will increase by just less than 10% to US$5.5 billion. By moving operations underground using the block-cave method, Seabridge says it can reduce waste rock by 81% or 2.4 billion tonnes over the 51-year mine life. Vastly increasing the amount of copper mined reduces life-of-mine operating costs to a negative US$179/oz. and pushes down all-in costs to just US$358 an ounce. Life-of-mine annual production is estimated at 592,000 ounces of gold, 286,000 pounds of copper and 2.8 million ounces of silver.